Various types of oxygen sensors have been proposed--see the referenced German Disclosure Document DE-OS No. 28 26 515, and U.S. Pat. No. 4,157,282, Riddel. DE-OS No. 28 26 515 relates to a sensor which has an essentially flat substrate made of electrically insulating material, or a material which, at least, has an electrically insulating surface. The substrate forms an elongated rectangular plate-like element and a material which responds to the composition of the surrounding atmosphere, for example ZrO.sub.2 can be placed on the electrodes which, on the side of the substrate, can extend in interleaved or interdigited form, or in other configurations. U.S. Pat. No. 4,157,282 is directed to maintain the air/fuel mixture supplied to an internal combustion engine at stoichiometric level by directing of stream of exhaust gases simultaneously across two opposite major faces of a zirconium dioxide solid electrolyte body to establish an output voltage between catalytic and non-catalytic gas-pervious electrodes which are, respectively, applied on faces of the body, to then derive a non-equilibrium oxygen content in the gases as a reference atmosphere and to then control the air/fuel mixtures in response to the electrical signal from the sensor. Sensors of these types require relatively long time until they reach their respective necessary operating temperature of about 700.degree. C.; the sensors can be heated, yet the time required for the sensors to reach operating temperature is comparativey long in spite of the low heat capacity of the sensor element itself.